Some engines use fuel injection systems to introduce fuel into the combustion chambers and/or a regeneration system of the engine. The fuel injection system may be any one of various types of fuel systems and may include, within the system, a number of fuel injectors. Among the various valves controlling the flow of fuel, a fuel injector may include at least one solenoid operated valve assembly. A solenoid operated valve assembly may include a solenoid and an associated valve. The solenoid may include a solenoid coil, a stator that acts as a magnet when the solenoid coil is provided with current, an armature, and a biasing or return spring. The armature is movable relative to the stator to actuate the valve.
When the solenoid coil is provided with current, a toroidal field of magnetic flux develops causing the armature to move relative to the stator. For example, the armature moves towards the stator upon energization of the solenoid coil. Upon cessation of current supplied to the solenoid coil, the return spring returns the armature to the original position, e.g., away from the stator. A typical fuel injection system requires this energization of the solenoid coil and subsequent movements of the armature repeatedly, rapidly, and with sufficient force. Consequently, the armature may potentially contact the stator due to various reasons. Contact between the armature and the stator potentially may cause damage to the stator surface. This, in turn, may cause loss of solenoid force and may result in injector performance change.
U.S. Patent Application Publication No. 2007/0028869 (the '869 publication), published on Feb. 8, 2007 in the name of Ibrahim et al., discloses one example of a fuel injector including a solenoid operated valve assembly. The '869 publication discloses an armature that moves relative to a stator during operation of the valve assembly. In the assembly of the '869 publication, at least one washer is utilized proximate the stator to facilitate insulation of undesired magnetic flux distributions to other portions of the fuel injector. Although the washer in the assembly of the '869 publication is located adjacent the stator, it is not situated so as to protect the stator from any potential contact by the armature. Accordingly, contact between the armature and the stator may occur.
The disclosed protection device for a solenoid operated valve assembly is directed to improvements in the existing technology.